Apparatus for cooling solid particulate material

ABSTRACT

Apparatus for cooling solid particulate material treated in a kiln comprising a plurality of elongated cylinders attached to the periphery of a rotary kiln. Particulate material is discharged from the kiln into the material inlet of the cooler while cooling air is introduced into the cooler countercurrent to the material flow. The particulate material is uniformly advanced from the material inlet to the outlet by means of a helical plate means which is continuous throughout its length. Annularly offset openings in the plate means deflect the cooling air from its initial flow path in order to increase the rate of heat transfer between the cooling gas and the particulate material, plate means and walls of the cooler. The plate means is easily manufactured and installed. The plate means is designed to prevent clogging by the particulate material. The interior of the cooler and the entire plate means are easily accessible for maintenance or repair by means of access doors near the material inlet and outlet. Spent gas is returned to the kiln to be used as preheated air of combustion.

United States Patent [l Kramm 5] May 7, 1974 APPARATUS FOR COOLING SOLID[57] ABSTRACT PARTICULATE MATERIAL Apparatus for cooling solidparticulate material [75] Inventor; Douglass Kramm, Allentown, treatedin a kiln comprising a plurality of elongated cylinders attached to theperiphery of a rotary kiln.

[7 Asslgnee: Fuller Company, Catasauqua, Particulate material isdischarged from the kiln into [22] Filed; Sept 4 1973 the material inletof the cooler while cooling air is in- Appl. No.: 394,214

Primary Examiner.lohn .l. Camby itq'zeytrlasnlaer Fi m efrankk t ThQIILQ J.

troduced into the cooler countercurrent to the material flow. Theparticulate material is uniformly advanced from the material inlet tothe outlet by means of a helical plate means which is continuousthroughout its length. Annularly offset openings in the plate meansdeflect the cooling air from its initial flow path in order to increasethe rate of heat transfer between the cooling gas and the particulatematerial, plate means and walls of the cooler. The plate means is easilymanufactured and installed. The platemeans is designed to preventclogging by the particulate material. The interior of the cooler and theentire plate means are easily accessible for maintenance orrepair bymeans of access doors near the material inlet and outlet. Spent gas isreturned to the kiln to be used as preheated air of combustion.

6 Claims, 8 Drawing Figures PATENTEDHAY 7 1974 I 8.809.528

sum 1 [IF 2 PATENTEDMAY 7 I974 SHEET 2 BF 2 FIG. 6.

APPARATUS FOR COOLING SOLID PARTICULATE MATERIAL BACKGROUND OF THEINVENTION The present invention provides attached tube coolers forcooling material treated in a kiln including an improved means forobtaining effective heat transfer.

Coolers arranged in a planetary fashion around the periphery of a rotarykiln have been used to cool particulate material discharged from thekiln for many years. Particulate material is fed into the material inletnear one end of a cooler as large quantities of the cooling gaseousfluid, usually air, is introduced countercurrent to the material flownear the material outlet. Spent air passes from the cooler through thematerial inlet into the kiln to be used as preheated air of combustion.

Coolers of the prior art have tried various means to increase the rateof heat transfer between the particulate material and the gaseous fluid.US. Pat. No. 1,905,744 is illustrative of helical plate'means attachedto the inner wall of the cooler which advance material at a uniformrate. By varying the pitch of the helix, the amount of time which theparticulate material is retained within the cooler can be controlled,subject to certain limitations imposed by the discharge rate ofparticulate material from the kiln. Cooling air is passed through theconcentric openings in the various plates which comprise the helix. Adisadvantage of this type of cooler is that much of the cooling air willnotcontact the particulate material, the plate means, or the interiorwalls of the cooler but will instead pass unobstructedly through theconcentric openings in the plate means from the inlet to the outlet.

In an effort to overcome the disadvantage described above, complexdiverting baffle plates were introduced within the openings of thehelical plate means in order to deflect the cooling air from its initialpath parallel to the axis of the cooler against the surfaces of theparticulate material, plate means, and the inner walls of the cooler andthereby achieve an increased rate of heat transfer for a given quantityof cooling fluid. The baffle plates of the prior art were difficult tomanufacture, install, and replace. The baffle plates were also subjectto clogging by the particulate material which may at times be binding oradhesive. During extreme conditions, a complete blockage of the coolerplate means may necessitate shutting down of the entire kiln operationin order to effect unclogging of one or more of the coolers. An accessopening must generally then be burned with a torch through the side wallof the cooler casing to permit unclogging of the plate means. shutdownsof the kiln operation and cleaning of the cooler in this manner causeextremely costly delays.

SUMMARY It is, therefore, the principal object of this invention toprovide an attached tube cooler for a rotary kiln which improves theheat exchange between the hot material and the cooling air.

It is another object of this invention to provide an improved cooler forhot particulate material which permits greater contact between the hotmaterial and the cooling air than can be achieved with prior cooler ofthe type to which the present invention relates.

It is a still further object of this invention to provide an attachedtube cooler for a rotary kiln which improves material advancementthrough the cooler.

The objects of the present invention will be achieved by providingapparatus for cooling solid particulate material treated in a rotarykiln including a plurality of elongated cylinders adapted to beconnected to the rotary kiln for rotation with said kiln about an axis;each of said cylinders having an inlet at one end for receiving hotsolid particulate material discharged from said kiln, an outlet at theother end for discharging cooled solid particulate material from saidcylinder; means adapted to be connected to said other end of saidcylinder for supplying cooling air to said cylinder whereby the coolingair passes through the cylinder, cools the hot material, is heated bythe hot material and is returned to the kiln as combustion air; andapparatus for improving heat exchange between the solid particulatematerial and the cooling air and controlling the movement of solidparticulate material from said inlet to said outlet comprising: asubstantially continuous helical plate means rigidly mounted in saidcylinder for increasing the rate of heat exchange by contact between thecooling air, solid particulate material and said plate means and havinga first flight near said cylinder outlet, a last flight near saidcylinder inlet and a plurality of flights intermediate said first andlast flights, each of said flights having at least one opening thereinfor the passage of cooling air therethrough; said opening in at leastthe first and last flight having a circular opening therethrough havingits center on the longitudinal axis of the cylinder; said opening in theflights intermediate said first and last flight having an openingsmaller than said circular opening and having its center offset from thecenter of said circular opening and being spaced angularly from theopening in the adjacent flights to thereby define a tortuous air flowpath through said cylinder; each of said openings being dimensioned topermit sufficient cooling air to pass through the cylinder to cool thematerial.

BRIEF DESCRIPTION OF THE DRAWINGS invention as taken along the lines 33of FIG. 1 in the direction of the arrows; and

FIGS. 4 through 8 aresectional views similar to FIG.

3 as taken along the lines 4-4 to 8-8, respectively, in FIG. 1 in thedirection of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I, a cooler of thepresent invention generally designated at 1 has been shown inrelationship to a rotary kiln which is shown generally as 2. The kiln 2is rotatably mounted on support roller bearings and kiln riding rings,both shown generally as 3, and is driven by conventional driving meansnot shown). The cooler 1 includes a plurality of elongated cylinders 4each attached to the discharge end of kiln 2 by any conventional meanssuch as welding (not shown). Since the cylinders 4 are fixed to the kiln2, as the kiln is rotated about its own axis, the cooler I will berotated about the longitudinal axis of the kiln.

Particulate material is discharged from kiln 2 by gravity into each.cylinder 4, in turn, as each cylinder rotates below the height of thekiln discharge outlet 6. After material has entered each cylinder 4, itwill contact the plate means of the present invention for heat transfer.Material enters cylinder 4 through material inlet 7 which is flowconnected to the kiln outlet 6. Particulate material is prevented fromreentering kiln 2 when cooler 1 is raised above the axis of the kiln byany conventional means, such as conduit 8 which extends into thematerial inlet 7 a distance greater than the normal height of thematerial bed in cooler 1. As material cascades down inlet section 9, itcontacts the plate means of the present invention shown generally as 10and specifically as 10a through 10f. It should be understood that thenumber of plate 'means and the helical pitch as shown in FIGS. 1 and 2are intended merely as schematic representations because these fac torswill vary for any cooler upon the rate of heat transfer sought to beachieved and .the quantity of cooling fluid which is used. Furthermore,while subsequently the cooling fluid will be referred to as air, itshould be understood that any inert gas may be used as a cooling mediumand should be considered within the scope of the present invention.

Particulate material will be advanced from the material inlet 7 to thematerial outlet 11 at a uniform rate by plate means 10 connected to theinner cooler walls 12 by any suitable means, such as welding. Airsupplied by any conventional means (not shown) enters the coolercountercurrent to the particulate material through gas inlet 15 andcommunicates with plate means 10 wherein the air is deflected from itsinitial path of flow parallel to the axis of the cylinder by plate means10 and is caused to contact the pulverulent material, the subsequentportions of plate means 10, and the inner cooler walls 12. It is wellknown that as the time in which the air is retained within the cooler 2is increased, the rate of heat transfer for a given quantity of air isalso increased.

Referring now to FIGS; 2, 3 and 9, plate means 10a and l0fare seen in aplane perpendicular to the axis of the cylinder as screw flights with aconcentric circular opening. Plate means 1% through 10e, shown in FIGS.4 through 7, respectively, are each seen in a plane perpendicular to theaxis of the cylinder as a screw flight which has an opening therethroughwhich is a circular section less than a complete circle. 1

Plate means 10a and 10f, which are considered tran sitional plates,provide surfaces 30' and 35' respectively, for advancing pulverulentmaterial while cooling air passes through circular openings and 25.Plate means 10b through We, however, have smaller openings, andconversely, larger surfaces to deflect cooling gas tortuously from'itsinitial flow path towards the inner cylinder walls 12 and towards thematerial which is being advanced through the cooler. More specificallyreferring to FIG. 2 and 4, plate means 10b is seen to have opening 21for the passage of cooling air therethrough and-surface 31 fordeflecting the air into intimate contact with the material to obtainheat transfer. Surface 31 is seen to block and deflect the air, forcingthe air through opening 21 towards surface 32 of subsequent plate means100. Plate means 100 may be partially viewed through opening 21 in FIG.4. A portion of the air will initially contact surface 32a and then beblocked and deflected tortuously towards surface 32b and through opening22in plate means 100.

Referring specifically to FIG. 5, opening 22 in plate 100 is seen as aportion of a circular opening through which surface 33 of plate 10d isvisible. Opening 22 may be formed by arc 50 and planar surfaces 51 and52.

It should be apparent that in forming helical plate means 10, surface bofa flat circular plate 10a would be joined as by welding to surface 31aofsubsequent plate 101; while surface 31b of the same plate 10b would bejoined to'surface 32a of subsequent plate 100. The joining of plates inthis manner will be continued until all subsequent surfaces 33 through35 are similarly joined to provide a helical plate means which iscontinuous throughout its length for uniformly advancing particulatematerial while permitting large portions of cooling air to tortuouslypass therethrough. Spent air which has passed through the last plate 10fwill be discharged from the cooler and enter the kiln to be used assecondary air of combustion. i

It is believed that the objects of the present invention will beeffectively achieved if the radius of'openings 20 through 25 areapproximately one-half to three-fourths the radius of the cylinder 4.This radius will permit surfaces 30' through 35 to be higher than thelevel of the bed of particulate material being advanced by the conveyinghelix. It should be readily understood that additional portions ofintermediate plate means similar to plate means l0b-through 10:: may beincluded within the scope of the invention for. longer coolers orincreased heat transfer and would be assembled and con nected to oneanother and to the inner cooler wall 12 by the same means such aswelding and in the same manner as illustratively described above. Theflow path of the air from the gas inlet 15 to the gas discharge, ifadditional plates are included, will be substantially similar throughoutthe length of the cooler as that which has been described with referenceto plate means 10b through 10e. Referring again to FIG. 1, access door40 has been providednear the material inlet portion 9 to permit accessto the interior of the cooler for inspection, mainteriance or repair.The arrangement of the plate means 10 of the present invention shouldenable a person to easily enter most coolers of conventional size forthese purposes. A second access door 41 may also be provided near thematerial outlet 5 for the same purposes of inspection, maintenance orrepair.

In the operation of the cooler l, the rotation of kiln 2 causesparticulate material to be discharged through kiln outlet 6 which isflow connected to cooler material inlet 7, through conduit 8, into thecooler inlet portion 9. The particulate material is uniformly advancedthrough cooler l by plate means 10 towards material discharge outlet 11.Cooling air enters cooler 1 through gas inlet 15 near material dischargeoutlet 11 countercurrent to the direction of flow of material andcontacts plate means 10 which deflects the gaseous fluid against thematerial and inner cooler walls 12. Spent air which has been heatedenters the kiln through the material inlet 7 to be used as preheated airof combustion.

The path of flow of the air may typically be described as passingthrough opening 20 in transition flight 10a whereupon a portion of theflow contacts surface 31 of flight 10b before being deflected upwardlyagainst the upper portion of the inner cooler wall 12 and downwardlytowards the particulate material which is advanced by surface 31'. Thegaseous fluid then passes through opening 21 in plate means b whereuponit initially contacts surface 32aand is then deflected laterallydownward, contacting particulate material between plate means 105 and10c, and then passes through the opening 22 in plate means 100 aftercontacting surfaces 32b and 33a. The air is deflected downwardly and theflow path of the air repeats the pattern described above wherein opening23 and surface 33 of plate means 10d correspond to opening 22 andsurface 32 of plate means 10c, respectively. While the air is contactingthe plate means as described above, the lower surfaces of plate means 10such as 30 through 35' are uniformly advancing particulate material fromthe material inlet. 7 towards the outlet 11 without the materialbecoming clogged between the plate means or without clogging theopenings. It will be understood that all of the air will be totallydeflected from its initial path parallel to the axis of the cylinderwithin a distance equivalent to twice the pitch of the conveying helixformed by the plate means 10b through 106. In this way the heat exchangebetween the air and the material can effectively be achieved.

Inspection, maintenance, and repair of most conventional coolers can beachieved by means of access doors 40 or 41 which will permit a person toenter the cooler. The arrangement and openings of plate means 10 willpermit an inspector or repairman to pass through the cooler without thenecessity of damaging the side of the cooler or plate means. It will bereadily appreciated by those skilled in the art that the variousportions of plate means 10 may be easily fabricated from individualcircular sections and fastened together by any suitable means such aswelding.

While the invention has been described above in reference to a coolerattached to a rotary kiln, it will be.

understood by those skilled in the art that the apparatus of the presentinvention can be applied to any heat transfer process such as drying orheating wherein gaseous fluid is communicated with the particulatematerial, plate means, and inner cylinder walls in an apparatusrotatably mounted and adapted to a source of power for rotating thecylinder. It is for this reason that it is desired that the invention belimited solely to that which is claimed below.

I claim:

1. Apparatus for cooling solid particulate material treatedin a rotarykiln including a plurality of elongated cylinders adapted to beconnected to the rotary kiln for rotation with said kiln about an axis;each of said cylinders having an inlet at one end for receiving hotsolid particulate material discharged from said kiln, an outlet at theother end for discharging cooled solid particulate material from saidcylinder; means adapted to be connected to said other end of saidcylinder for supplying cooling air to said cylinder whereby the coolingair passes through the cylinder, cools the hot material, is heated bythe hot material, and is returned to the kiln as combustion air; andapparatus for improving heat exchange between the solid particulatematerial and the cooling air and controlling the movement of solidparticulate material from said inlet to said outlet comprising:

a substantially continuous helical plate means rigidly mounted in saidcylinder for increasing the rate of heat exchange by contact between thecooling air, solid particulate material and said plate means and havinga first flight near said cylinder outlet, a last flight near saidcylinder inlet and a plurality of flights intermediate said first andlast flights, each of said flights having at least one opening thereinfor the passage of cooling air therethrough; said opening in at leastthe first and last flight having a circular opening therethrough havingits center on the longitudinal axis of the cylinder; said opening in theflights intermediate said first and last flight having an openingsmaller than said cylinder opening and having its center offset from thecenter of said cylinder opening, being spaced angularly from the openingin the adjacent flights to thereby define a tortuous air flow throughsaid cylinder;

each of said openings being dimensioned to permit sufficient cooling airto pass through the cylinder to cool the material.

2. The apparatus of claim 1 wherein said openings in the intermediateflights are angularly spaced apart to cause all of the gaseous fluid tobe deflected from a path parallel to the axis of said cylinder withinthe distance equivalent to twice the pitch of said helical plate.

3. The apparatus of claim 2 wherein the openings in said intermediateflights include, in a plane perpendicular to the axis of said platemeans, a substantially semicircular shape through which cooling airfirst passes and substantially a quarter circular section through whichcooling air subsequently passes.

4. The apparatus of claim 3 wherein each of said openings have a planarsurface which is from the planar surface of the opening in the adjacentflight.

5. The apparatus of claim 4 wherein said continuous helical plate meanshas an opening whichis continuous for the passage of cooling airtherethrough.

6. The apparatus of claim 5 wherein the radius of said opening isbetween approximately one-half to three fourths the radius of saidcylinder.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No- 3, 9 5Dated May 7,, 1974 Douglass J; Kramm Inventdfls) It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 6, line 2H, "cylinder" shouldread --cir*cular'-.

Column 6, line 26 "cylinder" should read'--circular--.

(SEAL) Attest:

McCOY M. GIBSON JR, Attesting Officer C. MARSHALL DANN Commissioner ofPatents USCOMM-DC GOING-P69 u. s. sovnunzu'r rnnmus OFFICE In o-su-su,

FORM PO-1050 (10-69)

1. Apparatus for cooling solid particulate material treated in a rotarykiln including a plurality of elongated cylinders adapted to beconnected to the rotary kiln for rotation with said kiln about an axis;each of said cylinders having an inlet at one end for receiving hotsolid particulate material discharged from said kiln, an outlet at theother end for discharging cooled solid particulate material from saidcylinder; means adapted to be connected to said other end of saidcylinder for supplying cooling air to said cylinder whereby the coolingair passes through the cylinder, cools the hot material, is heated bythe hot material, and is returned to the kiln as combustion air; andapparatus for improving heat exchange between the solid particulatematerial and the cooling air and controlling the movement of solidparticulate material from said inlet to said outlet comprising: asubstantially continuous helical plate means rigidly mounted in saidcylinder for increasing the rate of heat exchange by contact between thecooling air, solid particulate material and said plate means and havinga first flight near said cylinder outlet, a last flight near saidcylinder inlet and a plurality of flights intermediate said first andlast flights, each of said flights having at least one opening thereinfor the passage of cooling air therethrough; said opening in at leastthe first and last flight having a circular opening therethrough havingits center on the longitudinal axis of the cylinder; said opening in theflights intermediate said first and last flight having an openingsmaller than said cylinder opening and having its center offset from thecenter of said cylinder opening, being spaced angularly from the openingin the adjacent flights to thereby define a tortuous air flow throughsaid cylinder; each of said openings being dimensioned to permitsufficient cooling air to pass through the cylinder to cool thematerial.
 2. The apparatus of claim 1 wherein said openings in theintermediate flights are angularly spaced apart to cause all of thegaseous fluid to be deflected from a path parallel to the axis of saidcylinder within the distance equivalent to twice the pitch of saidhelical plate.
 3. The apparatus of claim 2 wherein the openings in saidintermediate flights include, in a plane perpendicular to the axis ofsaid plate means, a substantially semi-circular shape through whichcooling air first passes and substantially a quarter circular sectionthrough which cooling air subsequently passes.
 4. The apparatus of claim3 wherein each of said openings have a planar surface which is 90* fromthe planar surface of the opening in the adjacent flight.
 5. Theapparatus of claim 4 wherein said continuous helical plate means has anopening which is continuous for the passage of cooling air therethrough.6. The apparatus of claim 5 wherein the radius of said opening isbetween approximately one-half to three-fourths the radius of saidcylinder.